Portable display devices, such as cell phones, personal digital assistants (PDA's), or other hand held devices may employ an LCD display module, also referred to as a “smart LCD panel” such as those used in digital cameras and other devices. Such LCD display modules contain an embedded full frame memory, also referred to as an embedded still image buffer, which stores a single frame of digital data that is for display on an LCD display, also incorporated in the same package as the embedded still image buffer.
Portable display devices, such as cell phones or other suitable display devices increasingly attempt to provide additional functionality in the form of displaying full motion video. However, it is also important to employ efficient and display low cost solutions to facilitate this functionality. The LCD display module typically operates in two modes. One mode sometimes referred to as still frame mode, is used to store a single still frame of video such as a photograph or other suitable still image wherein the embedded still image buffer stores the digital data that is displayed as a still image on the LCD display. In a second mode, referred to as moving image mode, the embedded still image buffer is not employed, but instead manufactures of LCD display modules typically require another device that interfaces with the LCD display module to include a plurality of buffers so that external RAM must be included in the device or chip set that is coupled to the LCD display module when moving images are to be displayed. The requirement of additional RAM, typically in the form of a plurality of different frame buffers, adds cost and requires the use of scarce real estate, particularly when the portable display device is hand held portable display devices. As such, in typical portable display devices that employ LCD display modules, the embedded still image buffer (frame memory) is not used to display moving images and instead is typically only used in the still image mode of the LCD display module.
In addition when employing the moving image mode and hence the additional external RAM required for the moving image mode, a number of problems can arise related to video playback. For example, to facilitate a tradeoff between cost and performance, single display memories may be used in the moving image mode which can reduce the video playback quality since the single display memory may not be large enough for resolutions desired and may reduce video playback quality depending on the rate and efficiency of the video decoding. In addition, high current consumption occurs for example when displaying data on the LCD display. For portable display devices, reduction in current draw can greatly increase battery life. With the increase in demand for motion video playback on portable devices, such as the video playback of encoded video such as MPEG IV encoded video streams or other suitable video streams, it would be desirable to provide a cost effective solution to display motion video using conventional LCD display modules.